The invention relates to a drive device for an adjusting device for adjusting a vehicle component of a vehicle and to a method for operating a drive device.
Such a drive device is known from DE 197 51 861 A1 which discloses a drive device having an electronically commutated electric motor and an electronic control device in which the electronically commutated motor is provided with a sensor for sensing the rotational speed and/or the position of a rotor which interacts with a microcomputer of the control device in order to evaluate the sensor signals transmitted by the sensor. In order to drive the electronically commutated motor, an actuating voltage is applied to the electronically commutated motor via the electronic control device, the frequency and/or pulse width of which actuating voltage can be varied in order to adjust the rotational speed of the electronically commutated motor. The drive device also has a semiconductor output stage which is connected between the electronic control device and the electronically commutated motor in order to amplify the signal of the actuating voltage.
Electronically commutated motors have, compared to mechanically commutated motors, the advantage that the wearing parts which are necessary for mechanical commutation are dispensed with, and in particular no brushes are necessary for commutation, said brushes being subject to an increased degree to erosion and also giving rise to electromagnetic interference signals due to brush sparking, and therefore adversely affecting the EMC (electromagnetic compatibility) behavior.
An electronically commutated motor has a rotor and a stator which interact in order to drive the electronically commutated motor electrically. For this purpose, electrical windings are arranged in the stator, a current flowing through said windings and as a result generating an electromagnetic field which interacts with the rotor in such a way that the rotor is caused to rotate. In order to cause a current to flow in the electrical windings of the stator, an actuating voltage which can change over time is applied to the electronically commutated motor via an electronic control device.
In order to actuate the electronically commutated motor, an actuating voltage with a square-wave signal form is conventionally selected since as a result a maximum power output of the drive device which has a semiconductor output stage can be achieved and the square-wave signal form can be brought about by simply switching over the actuating voltage. However, such a square-wave signal form has the disadvantage that the acoustics of the drive device and the electromagnetic irradiation of the drive device can be increased. If, on the other hand, a sinusoidal signal is selected for the actuating voltage, the acoustics of the drive device is improved but the power output of the drive device is considerably worsened.